Improving effect of chronic resveratrol treatment on central monoamine synthesis and cognition in aged rats.

Resveratrol is a polyphenol exhibiting antioxidant and neuroprotective effects in neurodegenerative diseases. However, neuroprotective properties during normal aging have not been clearly demonstrated. We analyzed the in vivo effects of chronic administration of resveratrol (20 mg/kg/day for 4 weeks) in old male rats (Wistar, 20 months), on tryptophan hydroxylase (TPH) and tyrosine hydroxylase (TH) activities which mediate central monoaminergic neurotransmitters synthesis, and besides, on hippocampal-dependent working memory test (radial maze). Our results show an age-related decline in neurochemical parameters that were reversed by resveratrol administration. The resveratrol treatment enhances serotonin (5-HT) levels in pineal gland, in hippocampus, and in striatum, and those of noradrenaline (NA) in hippocampus and also dopamine (DA) in striatum. These changes were largely due to an increased activity of TPH-1 (463 % in pineal gland), TPH-2 (70-51 % in hippocampus and striatum), and TH (150-36 % in hippocampus and striatum). Additionally, the observed hippocampal effects correlate with a resveratrol-induced restorative effect on working memory (radial maze). In conclusion, this study suggests resveratrol treatment as a restoring therapy for the impaired cognitive functions occurring along normal aging process, by preventing 5-HT, DA, and NA neurotransmission decline.